The general direction of this investigation for the forthcoming year will continue essentially in the direction of last year's effort. PETT IV, which is installed in the Coronary Care Unit, will continue to be utilized for patient studies, specifically to define the natural history of the evolution of zones of myocardium at risk to areas of necrosis, and subsequently to objectively characterize the efficacy of potentially therapeutic interventions in modifying the ratio of myocardium ultimately undergoing necrosis with respect to the initial zone at risk. PETT VI, a positron emission device using cesium fluoride crystals, will be completed and put into use for cerebral and animal studies. In the Radiochemistry area, continued emphasis will be placed on the synthesis of high specific activity fluorinated compounds, particularly agents to map the dopamine receptors in the brain and for the study of myocardial function. Work will continue to be performed with isolated perfused rabbit hearts to characterize myocardial fatty acid metabolism after the administration of carbon-11-labeled palmitate. Studies utilizing PETT V will be carried out in intact dogs to define the distribution of the tracer. These studies will continue using PETT IV, upon its completion. The neurological effort will concentrate on the development of techniques for the measurement of brain glucose kinetics and distribution, blood flow, and oxygen consumption utilizing positron emission tomography. In the area of Nuclear Medicine, the project will involve the development and assessment of radiopharmaceuticals to measure tumor turnover and the level of estrogen receptors in breast carcinoma.